<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>Document</title>
	<style>
	.wp {
		width: 1000px;
		margin: auto;
	}

	.wp > div {
		float: left;
		height: 300px;
	}

	.left {
		background-color: red;
		width: 200px;
	}

	.center {
		background-color: green;
		width: 700px;
	}

	.right {
		background-color: blue;
		width: 100px;
	}

	@media screen and (min-width: 640px) and (max-width: 999px) {
		.wp {
			width: 640px;
			/*background-color: green;*/
		}
		.left {
			background-color: red;
			width: 100px;
		}

		.center {
			background-color: green;
			width: 540px;
		}

		.right {
			background-color: blue;
			width: 100%;
			float: none;
		}
	}

	@media screen and (max-width: 639px) {
		.wp {
			width: 100%;
			/*background-color: blue;*/
		}
		.left {
			background-color: red;
			width: 100%;
			float: none;
		}

		.center {
			background-color: green;
			width: 100%;
			float: none;
		}

		.right {
			background-color: blue;
			width: 100%;
			float: none;
		}
	}

	</style>
</head>
<body>

	<div class="wp">
		<div class="left">left</div>
		<div class="center">center</div>
		<div class="right">right</div>
	</div>
	
</body>
</html>